Coil type artificial kidneys in which non-woven screening is used as a membrane support are an important commercial therapeutic device, and are disclosed in U.S. Pat. Nos. 3,510,004 and 3,508,662. The use of such non-woven screening constituted an important advance in the art of dialysis, causing a significant reduction in price, and providing important functional advantages.
Attempts to produce even less expensive dialyzers have utilized embossed, ribbed sheeting as the membrane support for coil dialyzers, as is shown in U.S. Pat. No. 3,687,293. However, that structure has certain inherent functional disadvantages, in that it has been essentially unfeasible to obtain a very low flow resistance within the tubular membrane, and a correspondingly low pressure drop, coupled with a desirably low fluid volume within the tubular membrane.
In accordance with this invention, a ribbed sheeting membrane support is provided in which one of the sets of ribs is disposed in longitudinal relation to the axis of the tubular membrane, and both the flow resistance and the fluid volume of the tubular membrane can be improved, while permitting the use of the less expensive, ribbed support sheeting in place of the non-woven membrane support.